1-[2-fluoro-6-(trifluoromethyl)benzyl]-5-iodo-6-methylpyrimidine-2,4(1H,3H)-dione

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28th August 2018 to 7th September 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: MEP, P.R. China, the Guidelines for the Testing of Chemicals, Effects on Biotic Systems (the Second Edition), No. 202 "Daphnia sp., Acute Immobilisation Test". (2013.8)

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: EC, DG Health and Consumer Protection: Guidance on analytical quality control & validation procedures for pesticide residue analysis in food & feed SANCO/1257/2013 19/11/13 rev 0

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

1-{[2-fluoro-6-(trifluoromethyl)phenyl]methyl}-5-iodo-6-methyl-1,2,3,4-tetrahydropyrimidine-2,4-dione

EC Number:

687-893-6

Cas Number:

1150560-54-5

Molecular formula:

C13H9F4IN2O2

IUPAC Name:

1-{[2-fluoro-6-(trifluoromethyl)phenyl]methyl}-5-iodo-6-methyl-1,2,3,4-tetrahydropyrimidine-2,4-dione

Test material form:

solid: particulate/powder

Sampling and analysis

Analytical monitoring:

yes

Remarks:

HPLC - UV

Details on sampling:

Analysis frequency: in 0-hour fresh solution and 48-hour old solution

Test solutions

Details on test solutions:

Method of preparation of stock solution:
A stock solution of nominal concentration 500 mg/L was prepared with acetonitrile. A weight of 0.05002 g test item was dissolved in acetonitrile to 100 mL

Method of preparation of test solutions:
The stock solution was used to prepare the working standard solutions with acetonitrile of 0.05, 0.1, 0.5, 1.0, 5.0, 10 and 20mg/L

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnia of stock culture were originally obtained from the College of Applied Chemistry of China Agricultural University. The test Daphnia were derived from the same healthy pre-cultured population (i.e. showing no signs of stress such as high mortality, presence of males and ephippia, delay in the production of the first brood, discoloured animals, etc.). The pre-cultured animals were maintained in culture conditions (light, temperature, and medium) similar to those to be used in the test. The test animals were less than 24 hours old and not the first brood progeny. The batch used for this definitive test was Daphnia C20180829.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Post exposure observation period:

24 and 48 hours

Test conditions

Hardness:

140 - 250mg/L as (CaCO3)

Test temperature:

18-22 ± 1 °C

pH:

6.0 - 9.0

Dissolved oxygen:

Not less than 3mg/L during test period

Nominal and measured concentrations:

0.1503g of test item was weighed and made up to 1.5L with test water. The solution was stirred for 24 hours at 450rpm and then filtered with a 0.45μm membrane. 150, 203, 274, and 370ml were diluted to 500ml with test water.

The 5 nominal test concentrations used were: 30.0, 40.5, 54.8, 74.0 and 100mg/L.

The measured test concentration in fresh media was 0.349, 0.435, 0.626, 1.018 and 1.231mg/L. The measured test concentration in old media was 0.350, 0.443, 0.613, 1.007 and 1.214mg/L. The overall arithmetic mean determined concentrations was 0.350, 0.439, 0.620, 1.013 and 1.223mg/L. .

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass beakers
- Type: open
- Fill volume: 250ml
- Volume of solution: 100ml
- Aeration: none during the test period
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: water treated with Aquapro Pure Water System
- Total organic carbon: <2mg/L
- Alkalinity: pH 6.0 - 9.0

OTHER TEST CONDITIONS
- Photoperiod: 16 hours photoperiod daily, 8 hours dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : 24 and 48 hours. Animals not able to swim within 15 seconds after gentle agitation of the test vessel. Any abnormal behaviour or appearance was recorded.

RANGE-FINDING STUDY
- Test concentrations: 3, 10, 30 and 100mg/L
- Results used to determine the conditions for the definitive study: There was no inhibition for 3, 10 and 30mg/L and 100% inhibition for 100mg/L. The results of the preliminary test show that the 48 hour EC50 is within the range 30-100mg/L

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Results and discussion

Effect concentrations

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.57 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

During the 48-hour exposure period, no immobilisation or visible toxicity signs were observed in the control group and 30.0mg/L group. Immobilisation was observed in groups 40.5, 54.8, 74.0 and 100mg/L. 

Results with reference substance (positive control):

The 24 hour EC50 was 0.57mg/L with 95% confidence limits 1.06 ~ 1.41 mg/L

Reported statistics and error estimates:

Trimmed Spearman-Karber (TSK) method was used to derive the EC50 value and the corresponding 95% confidence limits.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

According to the results and based on the measured concentrations, the 48-hour median affect concentration (EC50) of Methyl Iodouracil to Daphnia magna was 0.57mg/L, with 95% confidence limits of 0.51 ~ 0.64mg/L.

Executive summary:

An Acute Immobilisation study of Methyl Iodouracil was conducted with Daphnia magna over a 48-hour exposure period.

Based on the results of the preliminary test, the definitive test was carried out at five nominal concentrations of 30.0, 40.5, 54.8, 74.0 and 100mg/L. The solution was filtered using a 0.45μm membrane. A blank control was performed concurrently. 4 replicates were used for the control and test concentrations with 5 daphnids for each replicate. The test was performed with a static water system over 48 hours. Dissolved oxygen and pH were measured at 0 hours and 48 hours during the exposure period in both control and test solutions. The temperature was monitored continuously by automatic temperature monitoring system and recorded. 

During the 48-hour exposure period, no immobilisation or visible toxicity signs were observed in the control group and 30.0mg/L group. Immobilisation was observed in groups 40.5, 54.8, 74.0 and 100mg/L. 

The  concentration  of  test  item  was  determined  in  samples  of test  media  by HPLC-UV.   

The results showed that for the test solutions of 30.0, 40.5, 54.8, 74.0 and 100mg/L, the measured test concentration in fresh media was 0.349, 0.435, 0.626, 1.018 and 1.231mg/L. The measured test concentration in old media was 0.350, 0.443, 0.613, 1.007 and 1.214mg/L. The overall arithmetic mean determined concentrations was 0.350, 0.439, 0.620, 1.013 and 1.223mg/L. 

According to the results and based on the measured concentrations, the 48-hour median affect concentration (EC₅₀) of Methyl Iodouracil to Daphnia magna was 0.57mg/L, with 95% confidence limits of 0.51 ~ 0.64mg/L.